Brian Boru

Brian Boru (941-23 April 1014) was King of Munster from 978 to 1014 (succeeding Mael Muad mac Brain and preceding Dungal mac Maelfothartaig Hua Donnchada) and High King of Ireland from 1002 to 1014 (interrupting Mael Sechnaill mac Domnaill's reigns).

Biography
Brian Boruma mac Cennetig was born in Killaloe, County Clare, Munster, Ireland in 941, the son of King Cennetig mac Lorcain of Tuadmuma. In 978, he led the Dalcassians to victory over Mael Muad mac Brain at Belach Lechta, destroying the Eoganachta and leading to the rise of the O'Brian dynasty of Munster with Brian as Munster's new king. In 1002, High King Mael Sechnaill mac Domnaill was forced to acknowledge the powerful Brian as the new High King, having previously divided Ireland between the two of them in 997. Brian forged a marriage alliance with the Norse of Dyflin by marring himself and his daughter to Dubliners, but, in 1014, the Dublin Norse and their allies from Sudreyjar attempted to overthrow Brian's rule, forcing Brian to ally with his former enemy Mael Sechnaill against the Norse. Brian confronted the Norse at the Battle of Clontarf, where he, his son, and grandson died in battle, despite winning a decisive victory over the Vikings and defeating their last major invasion of Ireland.